Embodiments of the invention relate to methods of calibrating a sensor configured to determine characteristics of a fluid. In particular, embodiments of the invention relate to calibration of sensors for determining a concentration of a diesel exhaust fluid (DEF).
Selective Catalytic Reduction (SCR) is a method of converting diesel oxides of nitrogen (NOx) emissions, by catalytic reaction, into diatomic benign nitrogen gas (N2) and water (H2O). In clean diesel engines, an SCR system delivers near-zero emissions of NOx.
DEF is used to reduce nitrous oxide (NOx) gases in the exhaust of diesel engines. DEF is a mixture of purified water and urea. In a typical SCR system, DEF is stored in a tank of a vehicle and is injected via one or more injectors into the exhaust at a ratio of about 1:50 to the diesel fuel being burned. The injected urea (in the form of a mist) mixes with the exhaust and breaks down NOx in the exhaust into nitrogen, water, and carbon dioxide.